PHOTODEPENDENT INHIBITION OF BOVINE SPLEEN NAD(-AZIDO CARBOCYCLIC ANALOGS OF NAD(+)()GLYCOHYDROLASE BY 8)

Carba-NAD(+) and pseudocarba-NAD(+), and their 8-azidoadenosyl derivat ives, were found to be good competitive inhibitors of calf spleen NAD( +) glycohydrolase. The 8-azido compounds, rested as photoaffinity labe ls, inhibited the enzyme in a light- and time-dependent manner; this i nhibition could be prevented by 3-aminopyridine adenine dinucleotide ( n(3)PdAD(+)), a competitive inhibitor of NAD(+) glycohydrolase. Irradi ation in the presence of the [H-3]-labeled 8-azido-carba-NAD(+) deriva tive resulted in an irreversible incorporation of the radioactivity in to the enzyme that could be largely prevented by addition of n(3)PdAD( +). These results indicate that carbocyclic-analogs of NAD(+) will be useful in identifying the substrate binding site of NAD(+) glycohydrol ase. (C) 1996 Academic Press, Inc.